Anchoring effects in audiovisual speech perception

Two experiments were conducted to investigate whether or not anchoring and selective adaptation induce basically the same psychological effects. The purpose of the first experiment is to show how an audiovisual anchor modifies the perception of consonant–vowel (CV) syllables. The anchors were two purely acoustical, two purely optical, and three audiovisual CV syllables. The results were compared with those of audiovisual speech selective-adaptation experiments conducted by Roberts and Summerfield [Percept. Psychophys. 30, 309–314 (1981)] and Saldaña and Rosenblum [J. Acoust. Soc. Am. 95, 3658–3661 (1994)]. The audiovisual anchoring effects were found to be very similar to the audiovisual selective-adaptation effects, but the incompatible audiovisual anchor produced more auditory-based contrast than the purely acoustical anchor or the compatible audiovisual anchor. This difference in contrast had not been found in the previous selective-adaptation experiments. The second experiment was conducted to directly compare audiovisual anchoring and selective-adaptation effects under the same stimuli and with the same subjects. It was found that the compatible audiovisual syllable (AbVb) caused more contrast in selective adaptation than in anchoring, although the discrepant audiovisual syllable (AbVg) caused no difference between anchoring and selective adaptation. It was also found that the anchor AbVg caused more auditory-based contrast than the anchor AbVb. It is suggested that the mechanisms behind these results are different.